Conventional electric water deicers are used to keep areas of livestock water tanks and ponds free from ice during winter months. Similarly, birdbath deicers and heated birdbaths or pet bowls are used for smaller animals. One type of deicer is a floating deicer in which a buoyant member such as a buoyant ring is attached to a heating element so that the deicer may float on the surface of the water. Another type of deicer is a sinking deicer that is configured to lay at the bottom of a tank or pond, or on a metal guard submerged in the tank. A drain plug deicer is yet another type of deicer that is mounted through a drain hole of a tank and operates similar to a sinking deicer.
Deicers typically include a temperature sensor (e.g., a thermostat) that detects when the water temperature rises above a freezing point. A typical deicer then deactivates a heating element when water is not susceptible to freezing in order to conserve energy. When the temperature sensor detects that the water temperature is at or close to the freezing point, the deicer re-activates the heating element in order to heat the water.
Typically, a deicer includes a single thermostat that is operable to deactivate the heater when water reaches a predetermined temperature. In some configurations, an additional path from the heater to the thermostat is employed to route heat to the thermostat if the deicer is removed from the water or if the containment vessel runs dry. In this case, cooler ambient air causes the deicer to activate and begin heating. Because there is no water to absorb the heat, however, the deicer and/or the containment vessel (such as a livestock water tank or birdbath) begin to heat. The heat reaches the thermostat quicker than normal because water mass is not present to absorb the energy. When the thermostat detects the predetermined deactivation temperature, it trips and the heater is deactivated. The ambient air then cools the deicer until the thermostat detects the predetermined activation temperature and the cycle repeats. The deicer continually cycles on and off even though the containment vessel is substantially or completely devoid of water. Consequently, energy is wasted and the heating element of the deicer typically reaches a much higher temperature in the absence of water, and may pose a fire hazard.
Typically, deicers are designed to trip and reset continually during normal operation in order to regulate the water temperature within a containment vessel between predetermined low and high temperatures. The thermostat closes to energize the heater when the water temperature drops to a point where freezing is possible and remains closed as the water is heated until it reaches the predetermined high temperature point when it opens (trips) and the heater deactivates. The thermostat typically remains open as the water cools until it once again closes and the cycle repeats.